Cooler

ABSTRACT

A cooler includes a substrate for disposing a semiconductor device thereon, a plate member fixed to a back surface of the substrate, a primary pipe, and a secondary pipe. A space sandwiched between the substrate and the primary pipe defines a first flow path for a coolant. The primary pipe and the secondary pipe configure a second flow path for a coolant. The secondary pipe is positioned to jet a coolant toward a region opposite to that having the semiconductor device disposed therein. The second flow path is separated from the first flow path.

TECHNICAL FIELD

The present invention relates to coolers, and particularly to coolersfor electric power converters.

BACKGROUND ART

In recent years, hybrid vehicles, electric vehicles, fuel cell vehicleshaving a fuel cell mounted therein, and other similar vehicles employingelectric power as a source of motive power are increasingly gainingattention. A hybrid vehicle is a vehicle employing a conventional engineand in addition thereto a motor as motive power. The hybrid vehicledrives the engine to obtain motive power and also converts directcurrent voltage that is received from a direct current power supply intoalternate current voltage which is in turn used to drive the motor toobtain motive power. An electric vehicle is a vehicle converting directcurrent voltage that is received from a direct current power supply intoalternate current voltage which is in turn used to drive the motor toobtain motive power.

Such vehicles employing electricity as a source of motive power has anelectric power converter mounted therein. The electric power converterincludes e.g., an inverter, a converter and/or a similar powersemiconductor device. The power semiconductor device includes e.g., apower MOSFET (Metal Oxide Semiconductor Field-Effect Transistor), anIGBT (Insulated Gate Bipolar Transistor), and the like.

An electric power converter mounted in a vehicle or the like may requirelarge electric power to provide the vehicle with high motive powerperformance. An electric power converter or the like of large electricpower generates a large quantity of heat. Accordingly a cooler ismounted to cool the electric power converter.

To cool an electric power converter or the like of large electric poweror a similar heat generating element, it is useful to bond a coolingplate (or fin) to a member that is directly adjacent to the electricpower converter or the like to transfer heat across an increased area tomore efficiently cool the element, or to cause a jet stream of coolantwater to impinge on a region that has the electric power convertertherein to cool it. Furthermore, it is effective to combine thesetechniques together.

Japanese Patent Laying-Open No. 2-100350 discloses a structure includinga cooling plate having a fin for cooling an integrated circuit. Thedisclosed structure includes: an integrated circuit having a pluralityof integrated circuit devices mounted on a substrate; a substrate frameholding the substrate; a cooling plate having a counter boring at asurface of the substrate opposite to the integrated circuit devices, andalso having a fin in the form of a sector disposed at a bottom surfaceof the counter boring; and a nozzle jetting a coolant to the center ofthe fin in the form of the sector. The publication discloses that thestructure can reduce thermal resistance between the integrated circuitdevices and the coolant and reduce the coolant in flow rate toefficiently discharge heat to outside the equipment.

Japanese Patent Laying-Open No. 5-3274 discloses a semiconductor coolingapparatus including: a plurality of semiconductor devices aligned on asubstrate; a coolant medium supplying header opposite to the substratewith a corresponding semiconductor device interposed therebetween; atubular coolant medium supplying member communicating with the coolantmedium supplying header; a coolant medium jetting outlet provided at anend of the coolant medium supplying member to jet a coolant medium thatis received from the coolant medium supplying header toward acorresponding semiconductor device; and a coolant medium return header.In this semiconductor cooling apparatus, the substrate is providedperpendicularly and a coolant medium return pipe is provided tocommunicate with the coolant medium return head, and a diaphragm memberis also provided to provide a diaphragm between the semiconductordevices. The publication discloses that this semiconductor coolingapparatus can prevent bubbles of the coolant medium generated at eachdevice from flowing to the other devices and cool each deviceindependently, and thus reduce the difference in temperature between thedevices.

Japanese Patent Laying-Open No. 6-112385 discloses a structure having aradiator and a nozzle combined together for cooling a semiconductordevice. In this structure the radiator has a bottom heat sink and firstand second perpendicular heat sinks and the bottom heat sink is providedat a heat radiating surface of a case mounted on an interconnectionsubstrate and having a semiconductor device mounted therein. The firstperpendicular heat sink is formed of a plurality of curved heatradiating plates. Their curved projecting surfaces face each other, andtherebetween a flow path for a jet stream is formed. The secondperpendicular heat sink is provided at a jet stream outlet of a pathformed by the first perpendicular heat sink, and the nozzle jets acoolant through the path formed by the first perpendicular heat sink tocause the coolant to impinge on the bottom heat sink. The publicationdiscloses that the structure allows the coolant that has once impingedin a jet stream to again impinge on a heat sink in a jet stream to moreefficiently cool the device without increasing the coolant in flowvelocity, flow rate or the like.

Japanese Patent Laying-Open No. 5-190716 discloses a semiconductorapparatus having on a multilayer ceramic substrate a large number ofintegrated circuit packages each having a cooling jacket attachedthereto. Each cooling jacket has a flexible tube connected thereto. Aflexible flow path is internally provided with a nozzle for causing acoolant fluid to flow into the cooling jacket in a jet stream in theform of a slit. The cooling jacket is internally provided with a fin,and a space for returning the coolant fluid. The publication disclosesthat the semiconductor apparatus can utilize water, which has a highability as a coolant, as a coolant medium, use a fin in the form of aflat plate helping to provide an increased heat transferring area, andprovide a jet stream in the form of a slit allowing each fin to receivethe coolant fluid uniformly, so that a semiconductor apparatus of anexcellent cooling structure can be provided.

When an electric power converter elevates in temperature, it may beimpaired in efficiency or a semiconductor device included in theelectric power converter may be damaged. Accordingly, as has beendescribed above, a cooler may be mounted to cool the electric powerconverter, and in particular, it is an important issue to cool theelectric power converter or a similar a heat generating elementaccommodating large electric power.

DISCLOSURE OF THE INVENTION

The present invention contemplates a cooler excellent in performance forcooling an electric power converter.

The present cooler includes: a substrate for disposing a heat generatingelement on one surface thereof; a heat radiating member fixed to another surface of the substrate; first flow path configuring means forconfiguring a first flow path formed to allow a coolant to contact theheat radiating member; and second flow path configuring means forconfiguring a second flow path formed to jet a coolant toward the othersurface opposite to a region having the heat generating element disposedtherein. The second flow path is separated from the first flow path.

In the present invention preferably the heat radiating member includesat least one of a plate member and a bar member.

In the present invention preferably the heat radiating member surroundsa region opposite to that having the heat generating element disposedtherein. The second flow path configuring means includes a primary piperemote from the other surface of the substrate, and a secondary pipeprojecting from the primary pipe toward the substrate. The secondarypipe is opposite to the region of the substrate having the heatgenerating element disposed therein. The first flow path includes aspace sandwiched between the primary pipe and the substrate.

In the present invention preferably the secondary pipe has an endsurface opposite to the substrate, and the end surface inclines toprovide a larger flow path in a direction in which the coolant flowsalong the first flow path configuring means.

In the present invention preferably the secondary pipe is tapered to benarrower toward the substrate.

In the present invention preferably the present cooler further includesthird flow path configuring means for discharging the coolant flowingthrough the second flow path. The third flow path configuring meansincludes a diaphragm between the primary pipe and the substrate. Thesecondary pipe penetrates the diaphragm. The secondary pipe is fixed tothe diaphragm without a gap.

In the present invention preferably the substrate has the one surfaceextending in one of a vertical direction and a direction inclinedrelative to the vertical direction.

In the present invention preferably the substrate has the one surfacefacing downward in a vertical direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general exploded perspective view of a semiconductorapparatus in a first embodiment.

FIG. 2 is a first general cross section of the semiconductor apparatusin the first embodiment.

FIG. 3 is a second general cross section of the semiconductor apparatusin the first embodiment.

FIG. 4 is a third general cross section of the semiconductor apparatusin the first embodiment.

FIG. 5 is a general exploded perspective view of a semiconductorapparatus in a second embodiment.

FIG. 6 is a first general cross section of the semiconductor apparatusin the second embodiment.

FIG. 7 is a second general cross section of the semiconductor apparatusin the second embodiment.

FIG. 8 is a general cross section of a semiconductor apparatus in athird embodiment.

FIG. 9 is a first general cross section of a semiconductor apparatus ina fourth embodiment.

FIG. 10 is a second general cross section of the semiconductor apparatusin the fourth embodiment.

BEST MODES FOR CARRYING OUT THE INVENTION First Embodiment

With reference to FIGS. 1 to 4, the present invention in a firstembodiment provides a cooler, as will be described hereinafter. In thepresent embodiment the cooler is a cooler for cooling an electric powerconverter as an object to be cooled.

The electric power converter includes an inverter for converting directcurrent electric power to alternate current electric power, a converterfor changing voltage, and other similar components. For example theelectric power converter includes a power MOSFET, an IGBT or an othersimilar power semiconductor device.

FIG. 1 is a general exploded perspective view of a semiconductorapparatus in the present embodiment. In the present embodiment thesemiconductor apparatus includes an electric power converter serving aselectronics, and a cooler for cooling the electric power converter.

In the present embodiment the semiconductor apparatus includes theelectric power converter that is implemented as a semiconductor device21. Semiconductor device 21 is formed to be rectangular as seen in aplane. Semiconductor device 21 is connected to an external electriccircuit (not shown). Semiconductor device 21 is a heat generatingelement generating heat when it is driven. In the present embodiment,semiconductor device 21 is an object to be cooled.

In the present embodiment the cooler includes a substrate 1 having onesurface with semiconductor device 21 disposed thereon. Substrate 1 is inthe form of a plate. In the present embodiment, substrate 1 has a frontsurface with a plurality of semiconductor devices 21 mounted thereon.Semiconductor device 21 is disposed to have a major surface bonded tosubstrate 1, as indicated by an arrow 54. In the present embodiment,substrate 1 includes a metal plate and an insulation layer deposited ona surface of the metal plate. Semiconductor device 21 is fixed on asurface of the insulation layer.

In the present embodiment the cooler includes a heat radiating memberfixed to a surface of substrate 1 that is opposite to that havingsemiconductor device 21 disposed thereon. In the present embodiment theheat radiating member includes a plate member 2. Plate member 2 is forexample a straight fin. Plate member 2 is provided at at least one of aregion opposite to that having semiconductor device 21 disposed thereinand a region surrounding the region opposite to that havingsemiconductor device 21 disposed therein. Plate member 2 is provided ata back surface of substrate 1. Plate member 2 is disposed to have amajor surface substantially perpendicular to a major surface ofsubstrate 1.

FIG. 2 is a first general cross section of the semiconductor apparatusin the present embodiment. FIG. 2 is a general cross section thereof cutat a plane parallel to the major surface of the substrate. Thesemiconductor apparatus's cooler includes a plurality of plate members 2disposed in alignment. Plate members 2 are disposed to have theirrespective major surfaces substantially parallel to one another. Platemember 2 is spaced from one another. Plate member 2 has a cutout portion2 a formed in a region having a secondary pipe 12, which will bedescribed later.

FIG. 3 is a second general cross section of the semiconductor apparatusin the present embodiment. FIG. 4 is a third general cross section ofthe semiconductor apparatus in the present embodiment. FIG. 3 is a crosssection taken along a line III-III in FIG. 2 and FIG. 4 is a crosssection taken along a line IV-IV in FIG. 2.

In the present embodiment, plate member 2 is formed to be rectangular asseen in a plane. Cutout portion 2 a is formed to provide a gap betweensecondary pipe 12 and an end of plate member 2. An arrow 51 indicates adirection in which a coolant medium flows. Plate member 2 is disposed tohave the major surface substantially parallel to the direction in whichthe coolant flows. Plate member 2 is formed to be substantially equal inheight to a first flow path described later.

With reference to FIGS. 1 to 4, in the present embodiment the coolerincludes first flow path configuring means formed to allow a coolant tocontact a heat radiating member. The first flow path configuring meansis formed to configure the first flow path for the coolant. In thepresent embodiment the first flow path configuring means includessubstrate 1 and a primary pipe 11 facing that side of substrate 1 whichhas plate member 2. A first flow path configuring member includes a wallmember 5 provided sideways of substrate 1 and primary pipe 11. The firstflow path is defined by a space surrounded by substrate 1, primary pipe11 and wall member 5.

In the present embodiment the cooler is formed to pass a first coolantthrough the first flow path sandwiched between substrate 1 and primarypipe 11. In the present embodiment a coolant supply device (not shown)is provided for supplying the first flow path of the cooler with acoolant.

In the present embodiment the cooler includes second flow pathconfiguring means formed to cause a second coolant to impinge on theback surface of substrate 1 at a region opposite to that having theelectric power converter disposed therein. The second flow pathconfiguring means is formed to jet the second coolant directly to theportion opposite to that having the electric power converter disposedthereon.

In the present embodiment the second flow path configuring means isformed to configure a second flow path for a coolant. The second flowpath configuring member includes primary pipe 11 spaced from the backsurface of substrate 1. Primary pipe 11 includes a flow path configuringplate 11 a and a flow path configuring plate 11 b spaced from each otherand having their respective major surfaces parallel to each other.Sideways of flow path configuring plates 11 a and 11 b, wall member 5 isprovided. A space surrounded by flow path configuring plates 11 a, 11 band wall member 5 defines a portion of the second flow path.

In the present embodiment the second flow path configuring meansincludes secondary pipe 12 projecting from primary pipe 11 towardsubstrate 1. Secondary pipe 12 is disposed opposite to the region ofsubstrate 1 that has semiconductor device 21 disposed therein. In thepresent embodiment, secondary pipe 12 is formed to be cylindrical.Secondary pipe 12 is formed to project from flow path configuring plate11 a. Secondary pipe 12 is formed to communicate with primary pipe 11.Secondary pipe 12 and primary pipe 11 configure the second flow path. Inthe present embodiment a coolant supply device (not shown) is providedto supply the second flow path with a second coolant.

In the present embodiment the first and second flow paths pass the firstand second coolants, respectively, of water. The first and second flowpaths are supplied with the coolant water by a common coolant supplydevice.

With reference to FIGS. 1 and 3, in the present embodiment, secondarypipe 12 has an end surface 12 a opposite to substrate 1. End surface 12a inclines to provide a larger flow path in the direction in which thefirst flow path passes the first coolant, as indicated by arrow 51. Morespecifically, end surface 12 a is formed to have a larger distance fromsubstrate 1 in the direction in which the first coolant flows. Endsurface 12 a is formed to have the inclined surface facing downstream ofthe first coolant.

With reference to FIGS. 2 to 4, semiconductor device 21 generates heat,which is transferred to substrate 1 and plate member 2. A coolant supplydevice supplies the first coolant, which is introduced into the firstflow path. The first coolant flows through a space sandwiched bysubstrate 1 and primary pipe 11, as indicated by arrow 51. The firstcoolant flows through the first flow path between plate members 2. Thefirst coolant flows in contact with plate member 2 and substrate 1. Asthe first coolant contacts plate member 2 and substrate 1, plate member2 and substrate 1 are cooled. Subsequently, the first coolant isexhausted.

Semiconductor device 21 is cooled via substrate 1 as plate member 2 iscooled. The heat of semiconductor device 21 is transferred to substrate1 and plate member 2, and radiated from substrate 1 and plate member 2to the first coolant.

The coolant supply device supplies the second coolant, which isintroduced into the second flow path configured by the second flow pathconfiguring member. The second coolant is introduced into primary pipe11, as indicated by an arrow 52. A portion of the second coolant flowingthrough primary pipe 11 flows into secondary pipe 12, as indicated by anarrow 53.

The second coolant flowing into secondary pipe 12 is discharged throughsecondary pipe 12 at end surface 12 a, as indicated by arrow 53. In thepresent embodiment the second coolant supplied through the second flowpath and thus separated from the first coolant does not contribute tocooling semiconductor device 21 before the second coolant is jetted outof secondary pipe 12. Before the second coolant is jetted out ofsecondary pipe 12, the second coolant does not contact plate member 2provided at the second flow path, and thus does not have its ability asa coolant impaired. The second coolant jetted out of secondary pipe 12impinges on the back surface of substrate 1 at the region opposite tothat having semiconductor device 21 disposed therein. More specifically,the second coolant cools by an impinging jet stream the region ofsubstrate 1 opposite to that having semiconductor device 21 disposedtherein. The second coolant that impinges on substrate 1 allowssemiconductor device 21 to be effectively cooled.

The second coolant impinging on substrate 1 flows through the first flowpath together with the first coolant, when the second coolant contactsand thus cools substrate 1 and plate member 2 as the second coolantproceeds. Subsequently the second coolant is exhausted together with thefirst coolant.

The present embodiment includes first flow path configuring means formedto allow a coolant to contact a heat radiating member, and second flowpath configuring means for causing an impinging jet stream to impinge ona region opposite to that having a semiconductor device disposedtherein, and a first flow path and a second flow path are separated. Inthe first flow path, the heat radiating member can be disposed toradiate heat across an increased area to efficiently remove heat. In thesecond flow path, a second coolant is supplied such that it is separatedfrom a first coolant until the second coolant is jetted out of asecondary pipe. The first coolant, which flows through the first flowpath, gradually increases in temperature as it approaches downstream ofthe first coolant. In contrast, the second coolant downstream issubstantially the same in temperature as that upstream. Thus the secondcoolant can impinge on semiconductor device 21 at low temperature andthus efficiently cool semiconductor device 21. Furthermore, the coolantcan be prevented from having its ability as a coolant impaired as itproceeds through a flow path and approaches downstream. Semiconductordevice 21 can be cooled substantially uniformly.

Thus, in the present embodiment, an impinging jet stream, and thecooling by convection of a heat transfer member can be providedsubstantially separately, and an object to be cooled can be cooledeffectively.

In the present embodiment the second flow path configuring meansincludes a primary pipe and a secondary pipe. A first flow path includesa space sandwiched between the primary pipe and a substrate. A platemember is disposed to surround a region opposite to that having asemiconductor device disposed therein. This configuration facilitatesforming the first flow path configuring means and the second flow pathconfiguring means. Furthermore a cooler having a simplifiedconfiguration can be provided.

With reference to FIGS. 1 and 3, in the present embodiment, secondarypipe 12 has end surface 12 a inclined to provide a larger path in adirection in which the first coolant flows. This configuration allows animpinging jet stream jetted from secondary pipe 12 to be guideddownstream of the first coolant.

In the present embodiment the cooler includes a substrate having asurface with a semiconductor device disposed thereon, that facesvertically upward. Alternatively, the cooler may have a substrate havinga surface with a semiconductor device disposed thereon, that facesvertically downward. This configuration allows bubbles generated in thefirst flow path or the second flow path to be guided to a side that isopposite to that having the substrate, and can thus prevent the bubblesfrom staying at the back surface of the substrate and removing a layerof liquid on the back surface of the substrate, and thus contributing toinefficient heat transfer.

Alternatively, the cooler may have the substrate disposed such that thesurface of the substrate that has a semiconductor device disposedthereon extends in a vertical direction or a direction inclined relativethe vertical direction. This configuration allows bubbles caused in thefirst flow path or the second flow path to be moved vertically upward.This can prevent the bubbles from staying at the back surface of thesubstrate. If bubbles are generated in the first flow path or the secondflow path, a layer of liquid can be ensured at the back surface of thesubstrate.

In particular, if the coolant is liquid and a large heat flux isprovided, vapors may be generated in the coolant. Any of the aboveconfigurations can expel such vapors from the cooler or move the vaporsto a periphery of the cooler. This can prevent an object to be cooledfrom being cooled inefficiently as bubbles are generated.

In the present embodiment a plate member serving as a heat radiatingmember is formed to be substantially equal in height to the first flowpath. This configuration allows the plate member to be provided alongthe entire height of the first flow path to transfer heat across anincreased area. This allows the first coolant to effectively cool anobject to be cooled.

In the present embodiment a plurality of semiconductor devices aredisposed in a direction in which a coolant flows, and for thesemiconductor devices, secondary pipes identical in geometry areprovided. However, the secondary pipes are not limited thereto, and maybe different from each other in size and geometry. Furthermore while inthe present embodiment the secondary pipe is cylindrical, it is notlimited thereto and may have any form.

For example, if different types of objects are to be cooled, then for anobject generating a large quantity of heat, a secondary pipe of a largediameter may be provided, and for an object generating a small quantityof heat, a secondary pipe of a small diameter may be provided. Thus inthe present embodiment the cooler can facilitate adjusting a quantity ofheat to be removed in accordance with each object to be cooled.

Furthermore, the secondary pipe or the primary pipe may be provided witha valve adjusting a flow rate of a coolant jetted through a particularsecondary pipe, a valve interrupting a flow through a particularsecondary pipe, and the like. This configuration allows an impinging jetstream to be adjusted in flow rate to correspond to a quantity of heatgenerated by an object to be cooled, and an impinging jet stream tointermittently cool an object to be cooled. Furthermore, if an object tobe cooled generates heat in a quantity varying in time series, then animpinging jet stream having a flow rate changed in accordance with suchvariation in the quantity of heat generated can be provided to optimallycool the object.

Furthermore in the present embodiment a plate member serving as a heatradiating member has a cutout portion. However, the plate member is notlimited thereto and may not have a cutout portion. For example, theplate member may penetrate the secondary pipe. Furthermore, the platemember is not limited to having a flat surface. It may be formed to havea curved surface.

In the present embodiment the first coolant and the second coolant areidentical. Alternatively, they may be different coolants. Furthermore,they are not limited to liquid and may contain gas.

Furthermore in the present embodiment the cooler is formed to have thefirst flow path and the second flow path passing the first coolant andthe second coolant, respectively, in a single direction. However, it isnot limited thereto, and may be formed to have the first flow path andthe second flow path passing the first coolant and the second coolant indifferent directions, respectively.

Furthermore the coolant supply device may be a coolant supply device forsupplying the first coolant and that for supplying the second coolant.Alternatively, it may include a circulation device circulating a coolantwhile cooling it.

In the present embodiment the object to be cooled is an electric powerconverter of large electric power by way of example. However, it is notlimited thereto, and the present invention is applicable to a cooler forany object to be cooled. For example, the present invention is alsoapplicable for example to coolers for an electric power converter ofsmall electric power and other objects to be cooled.

Second Embodiment

With reference to FIGS. 5 to 7, the present invention in a secondembodiment provides a cooler, as will now be described hereinafter. Inthe present embodiment the cooler is a cooler for cooling an electricpower converter. The cooler includes first flow path configuring meansand second flow path configuring means, similarly as described in thefirst embodiment. The present embodiment differs from the firstembodiment by a heat radiating member for radiating the heat of anobject to be cooled.

FIG. 5 is a general exploded perspective view of a semiconductorapparatus in the present embodiment. In the present embodiment the heatradiating member includes a bar member 3 fixed to and projecting fromthe back surface of substrate 1. In the present embodiment, bar member 3has a longitudinal direction substantially perpendicular to the backsurface of substrate 1.

FIG. 6 is a first general cross section of the semiconductor apparatusin the present embodiment. FIG. 6 is a general cross section as cut at aplane parallel to the major surface of the substrate. Bar member 3surrounds secondary pipe 12. Bar member 3 surrounds a region opposite tothat having semiconductor device 21 disposed therein. Bar member 3 isdisposed in a vicinity of the region opposite to that havingsemiconductor device 21 disposed therein. In the present embodiment,four bar members 3 are provided for a single semiconductor device 21.The first coolant flows in direction 51.

FIG. 7 is a second general cross section of the semiconductor apparatusin the present embodiment. FIG. 7 is a cross section taken along a lineVII-VII in FIG. 6. Bar member 3 is formed to have a length substantiallyequal to the height of the first flow path sandwiched between primarypipe 11 and substrate 1.

In the present embodiment the heat radiating member includes a barmember. The bar member can be varied in position, length, number, andthe like to allow the heat radiating member to remove heat at adifferent position and contact a coolant at a different area.

In the present embodiment bar members surround a region opposite to thathaving disposed therein an object to be cooled. Alternatively, the barmember may be provided at any position and in any number that do notprevent the second coolant having impinged on a surface of the substrateto be cooled from radically spreading and do not prevent the firstcoolant from flowing.

In the present embodiment the bar member is substantially equal inheight to the first flow path passing the first coolant. Thisconfiguration allows the bar member to be disposed along substantiallythe entire height of the first flow path to allow the first coolant toeffectively cool it.

The remainder in configuration, and function and effect is similar tothat of the first embodiment. Accordingly it will not be describedrepeatedly.

Third Embodiment

With reference to FIG. 8, the present invention in a third embodimentprovides a cooler, as will be described hereinafter. The cooler includesfirst flow path configuring means and second flow path configuringmeans, similarly as described in the first embodiment. The cooler of thepresent embodiment is different from that of the first embodiment in thegeometry of the heat radiating member and that of the secondary pipe ofthe second flow path configuring means.

FIG. 8 is a general cross section of the cooler in the presentembodiment. FIG. 8 is a general cross section as cut at a planeperpendicular to the major surface of the substrate. In the presentembodiment the cooler includes a secondary pipe 13 formed to projectfrom a surface of primary pipe 11. Secondary pipe 13 is formed to have across section in the form of a mountain. Secondary pipe 13 is tapered toprovide a narrower flow path toward substrate 1. In the presentembodiment, secondary pipe 13 is formed to have an end surfacesubstantially parallel to substrate 1.

In the present embodiment the cooler includes a plate member 4. Platemember 4 has a cutout portion 4 a. Cutout portion 4 a is formed toincline along the geometry of secondary pipe 13. Cutout portion 4 ainclines to have a cross section narrower toward substrate 1. Cutoutportion 4 a is formed to space plate member 4 from secondary pipe 13.

In the present embodiment the second coolant flowing in as indicated byarrow 52 is discharged from secondary pipe 13, as indicated by an arrow55. When the second coolant is discharged from secondary pipe 13, it isdischarged along the flow of the first coolant as indicated by arrow 51.Secondary pipe 13 that is tapered allows an impinging jet stream of thesecond coolant to smoothly join the first coolant. Furthermore, thesecondary pipe can be tapered variously to facilitate adjusting theimpinging jet stream in pressure and flow rate.

Furthermore, secondary pipe 13, configuring the second flow path, thatis tapered as seen in cross section can help the first coolant of thefirst flow path to approach substrate 1 and the second coolant havingimpinged on substrate 1 can be collected to substrate 1. This allows thesecond coolant to cool substrate 1 more effectively. Furthermore in thefirst flow path the first coolant and the second coolant can flow indifferent layers and thus be prevented from being mixed together. Smallpressure loss can thus be achieved.

The remainder in configuration, and function and effect is similar tothat of the first embodiment. Accordingly it will not be describedrepeatedly.

Fourth Embodiment

With reference to FIGS. 9 and 10, the present invention in a fourthembodiment provides a cooler, as will be described hereinafter. In thepresent embodiment the cooler includes the first flow path configuringmeans and the second flow path configuring means, and in addition, thirdflow path configuring means. More specifically in the present embodimentthe cooler has the first flow path and the second flow path, and inaddition, a third flow path. The third flow path is formed tocommunicate with the second flow path.

FIG. 9 is a first general cross section of the cooler in the presentembodiment. FIG. 9 is a general cross section as cut at a plane parallelto the major surface of the substrate. FIG. 10 is a second general crosssection of the cooler in the present embodiment. FIG. 10 is a crosssection taken along a line X-X in FIG. 9.

With reference to FIGS. 9 and 10, in the present embodiment the coolerincludes third flow path configuring means for configuring a third flowpath for discharging a coolant flowing through the second flow path. Thethird flow path configuring means includes a diaphragm 6. Diaphragm 6 isdisposed between primary pipe 11 and substrate 1. Diaphragm 6 is in theform of a flat plate. Diaphragm 6 is disposed to have a major surfacesubstantially parallel to the back surface of substrate 1. Diaphragm 6is disposed to divide the first flow path into two flow paths.

In the present embodiment the second flow path configuring memberincludes a secondary pipe 14. Secondary pipe 14 penetrates diaphragm 6.Secondary pipe 14 has a jet outlet in a space sandwiched betweensubstrate 1 and diaphragm 6. Secondary pipe 14 is fixed to diaphragm 6without a gap. More specifically, there is no gap between secondary pipe14 and diaphragm 6.

In the present embodiment the cooler includes the heat radiating memberthat is implemented by a plate member 7. Plate member 7 is formed topenetrate diaphragm 6. Plate member 7 has a cutout portion 7 a. Cutoutportion 7 a is formed to be circular as seen in a plane. Cutout portion7 a is formed along the geometry of secondary pipe 14.

In the present embodiment, the first flow path is defined by a spacesandwiched by primary pipe 11 and diaphragm 6. Furthermore, the thirdflow path is defined by a space sandwiched by substrate 1 and diaphragm6. Primary pipe 11 and secondary pipe 14 define the second flow path.

In the present embodiment the coolant supply device is formed to supplya coolant directly to the first flow path and the second flow path andavoid supplying a coolant directly to the third flow path.

In the present embodiment the first flow path and the second flow pathare isolated from each other. The first coolant cools plate member 7 asthe first coolant proceeds through the first flow path, as indicated byarrow 51. The second coolant flows through the second flow path and isjetted from secondary pipe 14, as indicated by arrow 53. The secondcoolant forms an impinging jet stream and thus cools the back surface ofsubstrate 1.

After the second coolant impinges on substrate 1, the second coolantflows through the third flow path. In the third flow path the coolantflows toward an exhaust port, as indicated by an arrow 56. In the thirdflow path the second coolant cools substrate 1 and plate member 7 as thesecond coolant proceeds. The first path is completely separated from thesecond and third paths.

In the present embodiment the cooler has a path cooling an object by animpinging jet stream and a path cooling the heat radiating member,separated from each other. The cooler is formed to prevent the secondcoolant forming an impinging jet stream and the first coolant coolingthe heat radiating member from being mixed together. This can reduce orprevent the interference of the first coolant cooling the heat radiatingmember with the second coolant forming the impinging jet stream, toallow the impinging jet stream to more effectively cool the object.

Alternatively, in the present embodiment, the cooler can avoid the firstcoolant and the second coolant mixed together. For example, the firstcoolant and the second coolant can be different coolants, respectively.In that case the coolant supply device can be a coolant supply deviceincluding a circulation device for the first coolant and that for thesecond coolant different than the first coolant.

Furthermore in the present embodiment a plate member has a cutoutportion and the cutout portion is formed along the geometry of asecondary pipe. The secondary pipe jets out the second coolant, whichspreads radially along the geometry of the secondary pipe. Thisconfiguration can prevent the plate member from significantly preventingthe second coolant from spreading.

The remainder in configuration, and function and effect is similar tothat of the first embodiment. Accordingly it will not be describedrepeatedly.

The present invention can thus provide a cooler providing excellentperformance to cool an electric power converter.

In the above described figures, identical or like potions areidentically denoted.

It should be understood that the embodiments disclosed herein areillustrative and non-restrictive in any respect. The scope of thepresent invention is defined by the terms of the claims, rather than thedescription above, and is intended to include any modifications withinthe scope and meaning equivalent to the terms of the claims.

Industrial Applicability

The present invention is applicable to a cooler. In particular, it isadvantageously applicable to a cooler for an electric power converter.

1. A cooler comprising: a substrate for disposing a heat generatingelement on one surface thereof; a heat radiating member fixed to another surface of said substrate; a first flow path configuring memberconfiguring a first flow path formed to allow a coolant to contact saidheat radiating member; and a second flow path configuring memberconfiguring a second flow path formed to jet a coolant toward said othersurface at a region opposite to a region having said heat generatingelement disposed therein, said second flow path being separated fromsaid first flow path.
 2. The cooler according to claim 1, wherein saidheat radiating member includes at least one of a plate member and a barmember.
 3. The cooler according to claim 1, wherein: said heat radiatingmember surrounds said region opposite to said region having said heatgenerating element disposed therein; said second flow path configuringmember includes a primary pipe remote from said other surface of saidsubstrate, and a secondary pipe projecting from said primary pipe towardsaid substrate; said secondary pipe is opposite to said region of saidsubstrates having said heat generating element disposed therein; andsaid first flow path includes a space sandwiched between said primarypipe and said substrate.
 4. The cooler according to claim 3, wherein:said secondary pipe has an end surface opposite to said substrate; andsaid end surface inclines to provide a larger flow path in a directionin which said coolant flows along said first flow path configuringmember.
 5. The cooler according to claim 3, wherein said secondary pipeis tapered to be narrower toward said substrate.
 6. The cooler accordingto claim 3, further comprising a third flow path configuring member fordischarging said coolant flowing through said second flow path, wherein:said third flow path configuring member includes a diaphragm betweensaid primary pipe and said substrate; said secondary pipe penetratessaid diaphragm; and said secondary pipe is fixed to said diaphragmwithout a gap.
 7. The cooler according to claim 1, wherein saidsubstrate has said one surface extending in one of a vertical directionand a direction inclined relative to said vertical direction.
 8. Thecooler according to claim 1, wherein said substrate has said one surfacefacing downward in a vertical direction.
 9. A cooler comprising: asubstrate for disposing a heat generating element on one surfacethereof; a heat radiating member fixed to an other surface of saidsubstrate; first flow path configuring means for configuring a firstflow path formed to allow a coolant to contact said heat radiatingmember; and second flow path configuring means for configuring a secondflow path formed to jet a coolant toward said other surface at a regionopposite to a region having said heat generating element disposedtherein, said second flow path being separated from said first flowpath.
 10. The cooler according to claim 9, wherein said heat radiatingmember includes at least one of a plate member and a bar member.
 11. Thecooler according to claim 9, wherein: said heat radiating membersurrounds said region opposite to said region having said heatgenerating element disposed therein; said second flow path configuringmeans includes a primary pipe remote from said other surface of saidsubstrate, and a secondary pipe projecting from said primary pipe towardsaid substrate; said secondary pipe is opposite to said region of saidsubstrate having said heat generating element disposed therein; and saidfirst flow path includes a space sandwiched between said primary pipeand said substrate.
 12. The cooler according to claim 11, wherein: saidsecondary pipe has an end surface opposite to said substrate; and saidend surface inclines to provide a larger flow path in a direction inwhich said coolant flows along said first flow path configuring means.13. The cooler according to claim 11, wherein said secondary pipe istapered to be narrower toward said substrate.
 14. The cooler accordingto claim 11, further comprising third flow path configuring means fordischarging said coolant flowing through said second flow path, wherein:said third flow path configuring means includes a diaphragm between saidprimary pipe and said substrate; said secondary pipe penetrates saiddiaphragm; and said secondary pipe is fixed to said diaphragm without agap.
 15. The cooler according to claim 9, wherein said substrate hassaid one surface extending in one of a vertical direction and adirection inclined relative to said vertical direction.
 16. The cooleraccording to claim 9, wherein said substrate has said one surface facingdownward in a vertical direction.